1. Field of the Invention
The present invention relates to an IP telephone and an IP telephone call method that enable a voice call over the Internet.
2. Description of Related Art
In recent years, various forms of IP telephone services that employ the VoIP (Voice over Internet Protocol) technology are provided (e.g., Related Art 1). As an example of the IP telephone services, an SIP server on an IP network connects a call, according to the SIP (Session Initiation Protocol), between an IP telephone at a caller terminal and an IP telephone at a receiver terminal. After the call is connected, the IP telephones exchange voice packets via the IP network, in order to realize the real-time telephone call.
In addition, IP TV telephones that can transmit image data together with voice data are being developed. For example, an integrated IP TV telephone, which is equipped with components such as a display, camera, IP telephone, and codec, has been introduced. Another type of IP TV telephone is a set-top box type IP telephone that includes a camera, microphone, and codec, the telephone functioning as an IP TV telephone by connecting to a TV.
[Related Art 1] Japanese Patent Laid-open Application 2003-219027
However, an IP telephone not having such a TV telephone function cannot transmit image data, along with voice data, to an opposing party. Therefore, it is impossible for both parties to exchange video images generated at its own side, so that the video images are displayed on a TV at the opposing party.